A toughened CPVC power cable protection pipe and a preparation method thereof

Abstract

The application discloses a toughened CPVC power cable protection pipe and a preparation method thereof, and relates to the technical field of polymer materials.The application comprises the following components in terms of weight parts: functionalized cage silsesquioxane 40-42 parts; composite modified magnesium hydroxide 80-85 parts; double-shell modifier 28-30 parts; stannic methoxide 30-31 parts; calcium stearate 3-3.5 parts; stearic acid 2-2.5 parts; antioxidant 2-3 parts; rutile titanium dioxide 15-16 parts; chlorinated polyethylene 55-60 parts; polyethylene wax 4-5 parts; ultraviolet absorber 1-1.5 parts; and chlorinated polyvinyl chloride 780-800 parts.The introduction of the functionalized cage silsesquioxane, the composite modified magnesium hydroxide, the double-shell modifier, the stannic methoxide and other raw materials effectively improves the flame-retardant capacity, the smoke suppression, the impact resistance at low temperature, the aging resistance and the heat resistance of the CPVC power cable protection pipe.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a toughened CPVC power cable protection pipe and its preparation method. Background Technology

[0002] Power cable protection pipes are specialized conduits used in power engineering for the laying and protection of underground power cables. Their core functions include electrical insulation, mechanical damage resistance, and resistance to environmental corrosion. They are crucial supporting materials for ensuring the safe and stable operation of transmission lines in scenarios such as urban power grid renovation, underground utility tunnel construction, and industrial park power distribution, and are widely used in the power infrastructure field. Among them, chlorinated polyvinyl chloride (CPVC) power cable protection pipes are the mainstream conduit material made with chlorinated polyvinyl chloride as the base resin. They possess excellent chemical corrosion resistance, electrical insulation, basic flame retardancy, and heat resistance, and are highly cost-effective, making them one of the most widely used conduit types in medium and low voltage underground cable laying projects.

[0003] However, in practical engineering applications, existing CPVC power cable protection pipes still have the following performance shortcomings: First, insufficient low-temperature impact resistance; the resin is inherently brittle, making it prone to cracking and damage under low-temperature winter environments or construction impacts, making it difficult to guarantee long-term protective stability. Second, poor synergy between flame retardancy and smoke suppression; although it has basic self-extinguishing properties, it produces a large amount of smoke and releases a lot of toxic gases during combustion, and conventional high-filler flame-retardant systems further exacerbate the pipe's brittleness. Third, insufficient heat resistance and aging resistance; under long-term underground humid and hot environments or cable overload conditions, it is prone to thermal deformation and mechanical property degradation, significantly shortening its service life. Fourth, poor synergy of comprehensive performance; existing modification technologies struggle to simultaneously achieve core properties such as flame retardancy, toughness, and heat resistance; improvements in a single property often come at the expense of other properties, failing to meet the diverse application needs of complex working conditions. Therefore, the flame retardancy, smoke suppression, low-temperature impact resistance, aging resistance, and heat resistance of existing CPVC power cable protection pipes still require systematic improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a toughened CPVC power cable protection pipe and its preparation method, thereby solving the following technical problems: Existing CPVC power cable protection pipes still have problems with poor flame retardancy, smoke suppression, low-temperature impact resistance, aging resistance and heat resistance.

[0005] The objective of this invention can be achieved through the following technical solutions: A toughened CPVC power cable protection pipe, comprising, by weight, 40-42 parts of functionalized cage-type silsesquioxane obtained by triethylamine catalytic addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyltriethoxysilane to obtain a functionalized silane monomer, followed by in-situ hydrolysis and condensation with silane coupling agent KH550; 80-85 parts of composite modified magnesium hydroxide obtained by stepwise in-situ coating modification of nano-magnesium hydroxide with tin tetrachloride pentahydrate, zinc sulfate heptahydrate and sodium borate decahydrate to obtain a composite coated magnesium hydroxide intermediate, followed by surface grafting modification with silane coupling agent KH550; tin tetrachloride pentahydrate and... Zinc sulfate heptahydrate is first hydrothermally crystallized at 160℃ and calcined at 600℃ to obtain a hollow zinc hydroxystannate core. Then, it is modified by in-situ grafting of silane coupling agent KH550 and functionalized silane monomers to obtain a core-shell structure intermediate. Then, it is modified by grafting terminal amino hyperbranched polyamide and solid-state mechanochemical milling to obtain a double-shell modifier of 28-30 parts; thiol methyltin 30-31 parts; calcium stearate 3-3.5 parts; stearic acid 2-2.5 parts; antioxidant 2-3 parts; rutile titanium dioxide 15-16 parts; chlorinated polyethylene 55-60 parts; polyethylene wax 4-5 parts; ultraviolet absorber 1-1.5 parts; and chlorinated polyvinyl chloride 780-800 parts.

[0006] Preferably, the preparation method of the functionalized cage-like silsesquioxane is as follows: A1: Under a nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyltriethoxysilane were added to anhydrous ethanol and heated to 75°C while stirring. After stirring for 20 min, triethylamine was added dropwise and stirred at 75°C for 8 h. After cooling, the mixture was vacuum evaporated to 150-160 g at 50°C. Then, dichloromethane was added and stirred for 20-30 min. Next, anhydrous magnesium sulfate was added and stirred for 20-30 min. Finally, the solid was filtered to remove it, and the dichloromethane was first vacuum evaporated at 40°C and then vacuum dried at 50-60°C for 20-30 min to obtain the functionalized silane monomer. A2: Under a nitrogen atmosphere, add silane coupling agent KH550 and anhydrous ethanol to the functionalized silane monomer and stir for 20-30 min. Then, add tetramethylammonium hydroxide ethanol aqueous solution dropwise and stir at 60℃ for 24 h. Adjust the pH to 6.8-7.2 and then rotary evaporate to 180 g under vacuum conditions of 50℃ and -0.09 MPa. Then, add n-hexane and stir for 30-50 min. After standing for 30-40 min, filter, wash and dry to obtain functionalized cage-type silsesquioxane.

[0007] Preferably, the mass ratio of anhydrous ethanol, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, vinyltriethoxysilane, triethylamine, dichloromethane, and anhydrous magnesium sulfate in A1 is 750:69.2:62-64:6:600:30; The mass ratio of the functionalized silane monomer, silane coupling agent KH550, anhydrous ethanol, tetramethylammonium hydroxide ethanol aqueous solution, and n-hexane in A2 is 100:73-75:300:40:400; The tetramethylammonium hydroxide aqueous solution contains 2.5% tetramethylammonium hydroxide by mass, and the mass ratio of water to ethanol is 1:1.

[0008] Preferably, the preparation method of the composite modified magnesium hydroxide is as follows: B1: Add nano-magnesium hydroxide to a mixture of anhydrous ethanol and deionized water and disperse it ultrasonically for 30-40 min while stirring. Then add tin tetrachloride pentahydrate and zinc sulfate heptahydrate 1 and stir for 30-40 min. After heating to 70℃, adjust the pH to 9 and stir at 70℃ for 3 h. Then adjust the pH to 8, add sodium borate decahydrate and zinc sulfate heptahydrate 2 and stir at 70℃ for 3 h. Finally, let it stand at 70℃ for 2 h, filter, wash and dry to obtain the composite coated magnesium hydroxide intermediate. B2: Add the composite-coated magnesium hydroxide intermediate to a mixture of anhydrous ethanol and deionized water and disperse it ultrasonically for 30-40 minutes while stirring. Then adjust the pH to 7.5-8.5 and add silane coupling agent KH550. Heat to 60℃ and stir for 4-5 hours. Then filter, wash and dry to obtain composite modified magnesium hydroxide.

[0009] Preferably, the mass ratio of anhydrous ethanol, deionized water, nano magnesium hydroxide, tin tetrachloride pentahydrate, zinc sulfate heptahydrate 1, sodium borate decahydrate, and zinc sulfate heptahydrate 2 in B1 is 300:300:120-130:28:31.3:25:17.

[0010] The mass ratio of anhydrous ethanol, deionized water, composite-coated magnesium hydroxide intermediate, and silane coupling agent KH550 in B2 is 300:300:200:5-6.

[0011] Preferably, the preparation method of the double-shell modifier is as follows: C1: Add tin tetrachloride pentahydrate and zinc sulfate heptahydrate to a mixture of deionized water and anhydrous ethanol and stir for 30 min. Heat to 65℃ and adjust pH to 10.2-10.5. Stir for another 2.5 h. Then add sodium dodecylbenzenesulfonate and urea and stir for 20 min. Crystallize at 160℃ for 12 h. After cooling, filter, wash and dry. Then calcine in a muffle furnace at 600℃ for 3 h. After cooling, obtain hollow zinc hydroxystannate core. C2: Under a nitrogen atmosphere, a hollow zinc hydroxystannate core was added to anhydrous toluene and ultrasonically dispersed for 40 min. Then, silane coupling agent KH550 and functionalized silane monomer were added. After stirring for 20 min, the temperature was raised to 80 °C. Triethylamine was then added dropwise and stirred for 6 h. After cooling, the mixture was filtered, washed, and dried to obtain a core-shell structure intermediate. C3: Under a nitrogen atmosphere, a core-shell structure intermediate was added to anhydrous methanol and ultrasonically dispersed for 30 min. Then, terminal amino hyperbranched polyamide was added and stirred for 30 min, followed by stirring at 55 °C for 10 h. After cooling, the mixture was filtered, washed, and dried. Subsequently, it was milled for 2 h at a pressure of 20 MPa and a speed of 180-200 r / min in a disc-shaped solid-phase chemical reactor. Finally, it was pulverized and passed through a 300-mesh sieve to obtain a double-shell modifier.

[0012] Preferably, the mass ratio of deionized water, anhydrous ethanol, tin tetrachloride pentahydrate, zinc sulfate heptahydrate, sodium dodecylbenzenesulfonate, and urea in C1 is 500:200:42:34.5-35:1.2:0.8-1.

[0013] Preferably, the mass ratio of anhydrous toluene, hollow zinc hydroxystannate core, silane coupling agent KH550, functionalized silane monomer, and triethylamine in C2 is 400:30-32:6-6.5:3:2.

[0014] Preferably, the mass ratio of anhydrous methanol, core-shell intermediate, and terminal amino hyperbranched polyamide in C3 is 300:25-30:18-22.

[0015] A method for preparing a toughened CPVC power cable protection pipe includes the following steps: S1: Dry chlorinated polyvinyl chloride at 80℃ for 5-6 hours, then mix at 55℃ for 2-3 minutes, then add methyl tin mercaptan, calcium stearate, stearic acid, and antioxidant and stir for 3 minutes. After raising the temperature to 75℃, add functionalized cage-type silsesquioxane and rutile titanium dioxide and stir for 4 minutes. Then raise the temperature to 88℃ and add composite modified magnesium hydroxide, double-shell modifier, and chlorinated polyethylene. After stirring for 5 minutes, raise the temperature to 115℃ and add polyethylene wax and ultraviolet absorber and stir for 2-3 minutes. Finally, while stirring, cool with water to 35-45℃ and discharge to obtain the mixture. S2: The extruded strip is melt-blended using a co-rotating twin-screw extruder. The extruded strip is immediately cooled and shaped in a constant temperature water bath at 35-40℃. Then, the surface moisture is blown off, and after pelleting, it is dried at 85℃ for 2-3 hours to obtain composite masterbatch. S3: The pipe is extruded and shaped using a single screw extruder, and then slowly cooled in a three-stage cooling water bath at 45℃, 35℃ and 25℃. After cooling, the pipe is cut to a fixed length to obtain toughened CPVC power cable protection pipe.

[0016] The beneficial effects of this invention are: This invention provides a toughened CPVC power cable protection pipe and its preparation method. The invention simultaneously improves the flame retardancy, smoke suppression, low-temperature impact resistance, aging resistance and heat resistance of the CPVC power cable protection pipe through the following methods.

[0017] (1) The functionalized cage-like silsesquioxane of the present invention is an organic-inorganic hybrid material with a cage-like inorganic rigid skeleton composed of silicon-oxygen bonds as the core, and phosphorus groups of phosphaphenanthrene are introduced through vinyl bridging and active amino groups are introduced through silane coupling agent components. When the protective tube is burning, the cage-like silsesquioxane skeleton will quickly migrate to the surface of the material to form a dense and continuous silicon-oxygen carbon layer, which isolates oxygen and heat transfer and inhibits melt dripping; the phosphorus groups decompose at high temperature to generate phosphoric acid derivatives, which catalyze the dehydration of the resin matrix to form carbon, and improve the residual carbon content and carbon layer density; the phosphorus oxygen free radicals generated by the decomposition of phosphorus groups can also capture hydrogen free radicals and hydroxyl free radicals in the combustion chain reaction and interrupt the combustion reaction; at the same time, the nanoscale dispersion structure can avoid the problem of small molecule migration and precipitation, and the flame retardant effect is long-lasting and stable. The synergistic catalytic carbonization effect of phosphorus and silicon can reduce volatile smoke precursors generated by the thermal decomposition of the matrix, thus reducing flue gas generation at the source. The dense silicon-oxygen carbon layer can adsorb and block the escape of flue gas and toxic gases, and the cage-like rigid framework can inhibit high-temperature cracking of the carbon layer, preventing flue gas from escaping through cracks. The rigid cage structure, as a nano-reinforcing point, can synergize with the elastic toughening components of the system to help terminate the propagation of microcracks. The active amino groups on the structure can form chemical bonds with the resin matrix and other filler surface groups, which can eliminate interface defects, avoid stress concentration during impact, and alleviate the inherent low-temperature brittleness of chlorinated polyvinyl chloride. Phosphoryl phenanthrene groups can capture active free radicals generated during thermo-oxidative and photo-oxidative aging, interrupting the aging chain reaction. The silicon-oxygen bond energy is much higher than that of the carbon-carbon bond, and the cage-like silicon-oxygen framework has excellent thermal stability, which can improve the thermo-oxidative aging resistance of the system. At the same time, the hybrid structure has good compatibility with the matrix, with no migration or precipitation problems, and can play a long-term aging resistance role. The high bond energy silicon-oxygen cage-like framework itself has excellent thermal stability, which can increase the initial thermal decomposition temperature of the material; the dense carbon layer formed by phosphorus-silicon synergy can delay the thermal decomposition process of the matrix; the chemical bonding between active amino groups and the matrix can increase the crosslinking density of the system and restrict the movement of polymer chain segments at high temperatures, thereby improving the material's heat resistance and deformation resistance.

[0018] (2) The composite modified magnesium hydroxide of this invention uses nano-magnesium hydroxide as the core, with a tin-zinc composite oxide layer and a borate synergistic layer successively coated on the surface. The outermost layer is an inorganic synergistic flame retardant and smoke suppressant filler that has been organically grafted and modified by a silane coupling agent. When the protective tube is burning, magnesium hydroxide decomposes at high temperature and absorbs a large amount of heat, reducing the surface temperature of the material. At the same time, it releases water vapor to dilute the concentration of combustible gas and oxygen. The tin-zinc composite oxide and borate coated on the surface will synergistically enhance the effect of magnesium hydroxide, catalyze the dehydration of the matrix into carbon, and strengthen the barrier effect. The outermost organic modified layer can achieve good dispersion of the filler in the matrix and avoid local flame retardant failure caused by agglomeration. Magnesium oxide, a decomposition product of magnesium hydroxide, can adsorb smoke particles and toxic hydrogen chloride gas. Tin-zinc composite oxide can catalyze the carbonization of smoke precursors, reduce the release of volatile organic compounds, and reduce the amount of smoke generated from the source. The high-temperature melting of borate forms a glassy coating layer, which further blocks the escape of smoke and significantly reduces the smoke density level of the material. The outermost layer of organosilane graft modification significantly reduces the interfacial tension between the filler and the resin matrix, forming a good interfacial bond. Surface organic modification eliminates interfacial defects, effectively preventing stress concentration and significantly improving the problem of a substantial decrease in low-temperature impact resistance caused by pure magnesium hydroxide filler. The surface-coated tin-zinc composite oxide has a certain absorption and shielding effect on ultraviolet light, reducing the irradiation damage to the resin matrix. The multi-layer coating structure prevents magnesium hydroxide from migrating and agglomerating in the matrix, maintaining a good dispersion state over a long period and reducing matrix defects during aging. The enhanced interfacial bonding force of the organic modification layer prevents performance degradation caused by interfacial debonding during aging, improving performance retention after aging. The high-temperature endothermic effect of magnesium hydroxide can delay the thermal deformation of the matrix; the tin-zinc composite oxide and borates can increase the thermal decomposition temperature of the matrix, promoting the rapid formation of a stable carbon layer at high temperatures; uniformly dispersed filler particles can form physical cross-linking points in the matrix, restricting the high-temperature movement of polymer chain segments, thereby increasing the Vicat softening temperature of the material.

[0019] (3) The double-shell modifier of the present invention is a multifunctional organic-inorganic hybrid modifier with a core-double-shell structure, consisting of a hollow zinc hydroxystannate core, a grafted phosphorus-silicon synergistic flame retardant layer as the inner shell, and a grafted end-amino hyperbranched polyamide as the outer shell. When the protective tube is burning, the hollow zinc hydroxystannate core can catalyze the dehydration of the matrix into char, while capturing combustion free radicals to interrupt the chain reaction; the inner shell phosphorus-silicon synergistic layer combines the gas-phase flame retardant and catalytic char formation effect of phosphorus-phenanthroline groups with the condensation phase barrier effect of siloxanes, forming a strong synergy with the core; the hyperbranched polyamide in the outer shell is rapidly carbonized at high temperature, further improving the strength and density of the char layer; the double-shell structure can achieve uniform dispersion of the modifier in the matrix, avoiding the agglomeration of the inorganic core, and significantly improving the flame retardant efficiency compared with unmodified, single-shell intermediates. The core zinc hydroxystannate is a highly efficient smoke-suppressing component that catalyzes the carbonization of smoke precursors, significantly reducing smoke production, while simultaneously adsorbing toxic hydrogen chloride gas and smoke particles. The dense carbon layer formed by the inner and outer shells prevents smoke escape. The hollow core structure further adsorbs smoke and toxic gases generated during combustion, simultaneously reducing smoke density and toxicity. The outer shell's amino-terminated hyperbranched polyamide has numerous active end groups and a flexible branched structure, exhibiting good compatibility and potential reactivity with the resin matrix. This strengthens interfacial bonding and effectively transfers and disperses impact stress. The hollow structure helps dissipate stress at the core-shell interface, buffering impact energy. Simultaneously, its uniform dispersion within the matrix terminates microcrack propagation. The double-shell structure effectively avoids the problem of interfacial debonding between the inorganic core and the organic matrix, reduces stress concentration points, and significantly improves the low-temperature brittleness of chlorinated polyvinyl chloride. The core zinc hydroxystannate and the inner shell siloxane components have a certain absorption and shielding effect on ultraviolet light, which can reduce the photo-oxidative degradation of the matrix; the active groups of the outer shell hyperbranched polyamide can capture the active free radicals generated during the aging process and interrupt the aging chain reaction; the double-shell structure can avoid the aggregation and migration of inorganic cores, maintain a stable dispersion state for a long time, reduce aging defects, and improve the performance retention rate of the material after aging.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention: The amino-terminated hyperbranched polyamide was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model: HyPer N102; the chlorinated polyvinyl chloride was purchased from Wuhan Jiyesheng Chemical Co., Ltd., item number: A00336; the chlorinated polyethylene was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: C909270; and the polyethylene wax was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: P903666.

[0023] Example 1: A method for preparing a toughened CPVC power cable protection pipe is as follows: S1: Under a high-purity nitrogen atmosphere and slightly positive pressure, 69.2g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 62g of vinyltriethoxysilane were added to 750g of anhydrous ethanol and heated to 75℃ while stirring at 300r / min. After stirring for 20min, 6g of triethylamine was added dropwise at 0.1g / min and stirred at 75℃ for 8h. After naturally cooling to room temperature, the mixture was rotary evaporated to 150g under vacuum at 50℃ and -0.09MPa. Then, 600g of dichloromethane was added and stirred for 20min. Next, 30g of anhydrous magnesium sulfate was added and stirred for 20min. Finally, the solid was filtered off and the dichloromethane was completely evaporated under vacuum at 40℃ and -0.09MPa. Then, the mixture was vacuum dried at 50℃ and -0.09MPa for 20min to obtain the functionalized silane monomer. S2: Under a nitrogen atmosphere and slightly positive pressure, 73g of silane coupling agent KH550 and 300g of anhydrous ethanol were added to 100g of functionalized silane monomer and stirred for 20min. Then, 40g of tetramethylammonium hydroxide ethanol aqueous solution (water to ethanol mass ratio of 1:1) with a mass fraction of 2.5% was added dropwise at 1g / min and stirred at 60℃ for 24h. After neutralization with glacial acetic acid, the solution was rotary evaporated to 180g under vacuum conditions of 50℃ and -0.09MPa. Then, 400g of n-hexane was added and stirred for 30min. After standing for 30min, the solution was filtered and the filter cake was washed three times with n-hexane (50g of n-hexane each time). Finally, the solution was dried at 80℃ and -0.09MPa for 12h to obtain functionalized cage-type silsesquioxane. S3: Add 120g of nano-magnesium hydroxide to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 30min. Then add 28g of tin tetrachloride pentahydrate and 31.3g of zinc sulfate heptahydrate and stir for 30min. After heating to 70℃, adjust the pH to 9 with a 10% sodium hydroxide aqueous solution and stir at 70℃ for 3h. Then adjust the pH to 8 with a 10% acetic acid solution. Then add 25g of sodium borate decahydrate and 17g of zinc sulfate heptahydrate and stir at 70℃ for 3h. Finally, let it stand at 70℃ for 2h for aging. After filtration, wash the precipitate 5 times with deionized water at 40℃ and dry at 120℃ for 4h to obtain the composite-coated magnesium hydroxide intermediate. S4: Add 200g of composite-coated magnesium hydroxide intermediate to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 30min. Then adjust the pH to 7.5 with a 10% sodium hydroxide aqueous solution and add 5g of silane coupling agent KH550. Heat to 60℃ and stir for 4h. Then filter and wash the precipitate three times with anhydrous ethanol. Finally, dry at 120℃ for 4h to obtain composite-modified magnesium hydroxide. S5: Add 42g of tin tetrachloride pentahydrate and 34.5g of zinc sulfate heptahydrate to a mixture of 500g deionized water and 200g anhydrous ethanol and stir for 30min. After heating to 65℃, adjust the pH to 10.2 with a 12% sodium hydroxide aqueous solution and keep it at the temperature for 2.5h. Then add 1.2g of sodium dodecylbenzenesulfonate and 0.8g of urea and stir for 20min. Then crystallize at 160℃ for 12h. After cooling to room temperature naturally, filter and wash the precipitate with deionized water until the filtrate is neutral. Then dry the precipitate at 120℃ for 6h and calcine it in a muffle furnace at 600℃ for 3h. After cooling naturally, hollow zinc hydroxystannate core is obtained. S6: Under a high-purity nitrogen atmosphere and slightly positive pressure, 30g of hollow zinc hydroxystannate core was added to 400g of anhydrous toluene and ultrasonically dispersed for 40min. Then, 6g of silane coupling agent KH550 and 3g of functionalized silane monomer were added, stirred for 20min, and heated to 80℃. Then, 2g of triethylamine was added dropwise and stirred for 6h. After cooling to room temperature, the mixture was filtered and the precipitate was washed three times with anhydrous toluene (50g of toluene each time). Finally, it was vacuum dried at 60℃ and -0.09MPa for 8h to obtain the core-shell structure intermediate. S7: Under a nitrogen atmosphere and slightly positive pressure, 25g of a core-shell structure intermediate was added to 300g of anhydrous methanol and ultrasonically dispersed for 30min. Then, 18g of terminal amino hyperbranched polyamide was added and stirred for 30min, followed by stirring at 55℃ for 10h. After cooling to room temperature, the mixture was filtered and the precipitate was washed four times with anhydrous methanol (50g methanol each time). Then, it was dried at 80℃ and -0.09MPa vacuum for 12h. Subsequently, it was milled for 2h in a milling disc solid-phase mechanochemical reactor at 20MPa pressure and 180r / min speed (the temperature of the circulating cooling water in the milling disc was 20℃ during the milling process). Finally, it was pulverized and passed through a 300-mesh sieve to obtain a double-shell modifier. S8: Dry 780g of chlorinated polyvinyl chloride at 80℃ for 5h, then mix at 55℃ for 2min at 500r / min. Then add 30g of methyl tin mercaptan, 3g of calcium stearate, 2g of stearic acid, 1g of antioxidant 1010, and 1g of antioxidant 168 and stir at 1200r / min for 3min. After raising the temperature to 75℃, add 40g of functionalized cage-type silsesquioxane and 15g of rutile titanium dioxide and stir at 1200r / min for 4min. Then raise the temperature to 88℃ and add 80g of composite modified magnesium hydroxide, 28g of double-shell modifier, and 55g of chlorinated polyethylene. After stirring for 5min, raise the temperature to 115℃ and add 4g of polyethylene wax and 1g of ultraviolet absorber UV-531 and stir for 2min (at this time, the material temperature does not exceed 120℃). Finally, while stirring at 300r / min, cool with water to 35℃ and discharge to obtain the mixture. S9: A co-rotating twin-screw extruder is used for melt blending with a screw length-to-diameter ratio of 40:1, a feeding and conveying section at 145°C, a compression section at 155°C, a plasticizing section at 165°C, a homogenizing section at 175°C, a venting section at 170°C, a die head connection section at 180°C, a die head orifice at 175°C, a screw speed of 180 r / min, and a vacuum degree of -0.08 MPa or higher in the vacuum venting section. The extruded strips are immediately cooled and shaped in a constant temperature water bath at 35°C, then the surface moisture is dried by an air dryer, and after pelleting, they are dried at 85°C for 2 hours to obtain composite masterbatch. S10: The pipe is extruded and shaped using a single screw extruder with a screw length-to-diameter ratio of 28:1, a screw compression ratio of 2.8:1, a feeding section temperature of 155℃, a compression section temperature of 165℃, a metering section temperature of 175℃, a die head connection section temperature of 180℃, a die temperature of 182℃, a screw speed of 30r / min, a traction speed and an extrusion speed of 1m / min, and a vacuum degree of -0.08MPa in the vacuum sizing sleeve. After that, it is slowly cooled in a three-stage cooling water bath at 45℃, 35℃ and 25℃. The cooled pipe is then cut to a fixed length to obtain a toughened CPVC power cable protection pipe.

[0024] Example 2: A method for preparing a toughened CPVC power cable protection pipe is as follows: S1: Under a high-purity nitrogen atmosphere and slightly positive pressure, 69.2g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 63g of vinyltriethoxysilane were added to 750g of anhydrous ethanol and heated to 75℃ while stirring at 300r / min. After stirring for 20min, 6g of triethylamine was added dropwise at 0.11g / min and stirred at 75℃ for 8h. After naturally cooling to room temperature, the mixture was rotary evaporated to 155g under vacuum at 50℃ and -0.09MPa. Then, 600g of dichloromethane was added and stirred for 25min. Next, 30g of anhydrous magnesium sulfate was added and stirred for 25min. Finally, the solid was filtered off and the dichloromethane was completely evaporated under vacuum at 40℃ and -0.09MPa. Then, the mixture was vacuum dried at 55℃ and -0.09MPa for 25min to obtain the functionalized silane monomer. S2: Under a nitrogen atmosphere and slightly positive pressure, 74g of silane coupling agent KH550 and 300g of anhydrous ethanol were added to 100g of functionalized silane monomer and stirred for 25min. Then, 40g of tetramethylammonium hydroxide ethanol aqueous solution (water to ethanol mass ratio of 1:1) with a mass fraction of 2.5% was added dropwise at 1g / min and stirred at 60℃ for 24h. After neutralization with glacial acetic acid, the solution was rotary evaporated to 180g under vacuum conditions of 50℃ and -0.09MPa. Then, 400g of n-hexane was added and stirred for 40min. After standing for 35min, the solution was filtered and the filter cake was washed 4 times with n-hexane (50g of n-hexane each time). Finally, the solution was dried at 80℃ and -0.09MPa for 14h to obtain functionalized cage-type silsesquioxane. S3: Add 125g of nano-magnesium hydroxide to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 35min. Then add 28g of tin tetrachloride pentahydrate and 31.3g of zinc sulfate heptahydrate and stir for 35min. After heating to 70℃, adjust the pH to 9 with a 10% sodium hydroxide aqueous solution and stir at 70℃ for 3h. Then adjust the pH to 8 with a 10% acetic acid solution. Then add 25g of sodium borate decahydrate and 17g of zinc sulfate heptahydrate and stir at 70℃ for 3h. Finally, let it stand at 70℃ for 2h for aging. After filtration, wash the precipitate 6 times with deionized water at 40℃ and dry at 120℃ for 5h to obtain the composite-coated magnesium hydroxide intermediate. S4: Add 200g of composite-coated magnesium hydroxide intermediate to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 35min. Then adjust the pH to 8 with a 10% sodium hydroxide aqueous solution and add 5.5g of silane coupling agent KH550. Heat to 60℃ and stir for 4.5h. Then filter and wash the precipitate three times with anhydrous ethanol. Finally, dry at 120℃ for 4h to obtain composite-modified magnesium hydroxide. S5: Add 42g of tin tetrachloride pentahydrate and 34.8g of zinc sulfate heptahydrate to a mixture of 500g deionized water and 200g anhydrous ethanol and stir for 30min. After heating to 65℃, adjust the pH to 10.4 with a 12% sodium hydroxide aqueous solution and keep it at the same temperature for 2.5h. Then add 1.2g of sodium dodecylbenzenesulfonate and 0.9g of urea and stir for 20min. Then crystallize at 160℃ for 12h. After cooling to room temperature naturally, filter and wash the precipitate with deionized water until the filtrate is neutral. Then dry the precipitate at 120℃ for 6h and calcine it in a muffle furnace at 600℃ for 3h. After cooling naturally, hollow zinc hydroxystannate core is obtained. S6: Under a high-purity nitrogen atmosphere and slightly positive pressure, 31g of hollow zinc hydroxystannate core was added to 400g of anhydrous toluene and ultrasonically dispersed for 40min. Then, 6.3g of silane coupling agent KH550 and 3g of functionalized silane monomer were added. After stirring for 20min, the temperature was raised to 80℃, and then 2g of triethylamine was added dropwise and stirred for 6h. After cooling to room temperature, the mixture was filtered and the precipitate was washed 4 times with anhydrous toluene (50g of toluene each time). Finally, the mixture was vacuum dried at 60℃ and -0.09MPa for 8h to obtain the core-shell structure intermediate. S7: Under a nitrogen atmosphere and slightly positive pressure, 28g of a core-shell structure intermediate was added to 300g of anhydrous methanol and ultrasonically dispersed for 30min. Then, 20g of terminal amino hyperbranched polyamide was added and stirred for 30min, followed by stirring at 55℃ for 10h. After cooling to room temperature, the mixture was filtered and the precipitate was washed four times with anhydrous methanol (50g methanol each time). Then, it was dried at 80℃ and -0.09MPa vacuum for 12h. Subsequently, it was milled for 2h in a milling disc-shaped solid-phase mechanochemical reactor at 20MPa pressure and 190r / min speed (the temperature of the circulating cooling water in the milling disc was 20℃ during the milling process). Finally, it was pulverized and passed through a 300-mesh sieve to obtain a double-shell modifier. S8: Dry 790g of chlorinated polyvinyl chloride at 80℃ for 5.5h, then mix at 55℃ at 500r / min for 2.5min. Next, add 30.5g of methyltin mercaptan, 3.3g of calcium stearate, 2.3g of stearic acid, 1.3g of antioxidant 1010, and 1.3g of antioxidant 168, and stir at 1200r / min for 3min. After raising the temperature to 75℃, add 41g of functionalized cage-type silsesquioxane and 15.5g of rutile dioxide. Titanium was stirred at 1200 r / min for 4 min, then the temperature was raised to 88℃ and 82.5 g of composite modified magnesium hydroxide, 29 g of double-shell modifier, and 57.5 g of chlorinated polyethylene were added. After stirring for 5 min, the temperature was raised to 115℃ and 4.5 g of polyethylene wax and 1.3 g of ultraviolet absorber UV-531 were added and stirred for 2.5 min (at this time the material temperature does not exceed 120℃). Finally, the mixture was stirred at 300 r / min and cooled to 40℃ with water. The mixture was then discharged to obtain the final product. S9: A co-rotating twin-screw extruder is used for melt blending with a screw length-to-diameter ratio of 45:1, a feeding and conveying section at 145°C, a compression section at 155°C, a plasticizing section at 165°C, a homogenizing section at 175°C, a venting section at 170°C, a die head connection section at 180°C, a die head orifice at 175°C, a screw speed of 180 r / min, and a vacuum degree of -0.08 MPa or higher in the vacuum venting section. The extruded strips are immediately cooled and shaped in a constant temperature water bath at 38°C, then the surface moisture is dried by an air dryer, and after pelleting, they are dried at 85°C for 2.5 hours to obtain composite masterbatch. S10: The pipe is extruded and shaped using a single screw extruder with a screw length-to-diameter ratio of 29:1, a screw compression ratio of 3:1, a feeding section temperature of 155℃, a compression section temperature of 165℃, a metering section temperature of 175℃, a die head connection section temperature of 180℃, a die temperature of 182℃, a screw speed of 30r / min, a traction speed and an extrusion speed of 1.3m / min, and a vacuum degree of -0.08MPa in the vacuum sizing sleeve. After that, it is slowly cooled in a three-stage cooling water bath at 45℃, 35℃ and 25℃. The cooled pipe is then cut to a fixed length to obtain a toughened CPVC power cable protection pipe.

[0025] Example 3: A method for preparing a toughened CPVC power cable protection pipe is as follows: S1: Under a high-purity nitrogen atmosphere and slightly positive pressure, 69.2 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 64 g of vinyltriethoxysilane were added to 750 g of anhydrous ethanol and heated to 75 °C while stirring at 300 r / min. After stirring for 20 min, 6 g of triethylamine was added dropwise at 0.12 g / min and stirred at 75 °C for 8 h. After naturally cooling to room temperature, the mixture was rotary evaporated to 160 g under vacuum at 50 °C and -0.09 MPa. Then, 600 g of dichloromethane was added and stirred for 30 min. Next, 30 g of anhydrous magnesium sulfate was added and stirred for 30 min. Finally, the solid was filtered off and the dichloromethane was completely evaporated under vacuum at 40 °C and -0.09 MPa. Then, the mixture was vacuum dried at 60 °C and -0.09 MPa for 30 min to obtain the functionalized silane monomer. S2: Under a nitrogen atmosphere and slightly positive pressure, 75g of silane coupling agent KH550 and 300g of anhydrous ethanol were added to 100g of functionalized silane monomer and stirred for 30min. Then, 40g of tetramethylammonium hydroxide ethanol aqueous solution (water to ethanol mass ratio of 1:1) with a mass fraction of 2.5% was added dropwise at 1g / min and stirred at 60℃ for 24h. After neutralization with glacial acetic acid, the solution was rotary evaporated to 180g under vacuum conditions of 50℃ and -0.09MPa. Then, 400g of n-hexane was added and stirred for 50min. After standing for 40min, the solution was filtered and the filter cake was washed 5 times with n-hexane (50g of n-hexane each time). Finally, the solution was dried at 80℃ and -0.09MPa for 16h to obtain functionalized cage-type silsesquioxane. S3: Add 130g of nano-magnesium hydroxide to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 40min. Then add 28g of tin tetrachloride pentahydrate and 31.3g of zinc sulfate heptahydrate and stir for 40min. After heating to 70℃, adjust the pH to 9 with a 10% sodium hydroxide aqueous solution and stir at 70℃ for 3h. Then adjust the pH to 8 with a 10% acetic acid solution. Then add 25g of sodium borate decahydrate and 17g of zinc sulfate heptahydrate and stir at 70℃ for 3h. Finally, let it stand at 70℃ for 2h for aging. After filtration, wash the precipitate 7 times with deionized water at 40℃ and dry at 120℃ for 6h to obtain the composite-coated magnesium hydroxide intermediate. S4: Add 200g of composite-coated magnesium hydroxide intermediate to a mixture of 300g anhydrous ethanol and 300g deionized water. While stirring at 800r / min, ultrasonically disperse at 200W power for 40min. Then adjust the pH to 8.5 with a 10% sodium hydroxide aqueous solution and add 6g of silane coupling agent KH550. Heat to 60℃ and stir for 5h. Then filter and wash the precipitate three times with anhydrous ethanol. Finally, dry at 120℃ for 4h to obtain composite-modified magnesium hydroxide. S5: Add 42g of tin tetrachloride pentahydrate and 35g of zinc sulfate heptahydrate to a mixture of 500g deionized water and 200g anhydrous ethanol and stir for 30min. After heating to 65℃, adjust the pH to 10.5 with a 12% sodium hydroxide aqueous solution and keep it at the temperature for 2.5h. Then add 1.2g of sodium dodecylbenzenesulfonate and 1g of urea and stir for 20min. Then crystallize at 160℃ for 12h. After naturally cooling to room temperature, filter and wash the precipitate with deionized water until the filtrate is neutral. Then dry the precipitate at 120℃ for 6h and calcine it in a muffle furnace at 600℃ for 3h. After natural cooling, obtain the hollow zinc hydroxystannate core. S6: Under a high-purity nitrogen atmosphere and slightly positive pressure, 32g of hollow zinc hydroxystannate cores were added to 400g of anhydrous toluene and ultrasonically dispersed for 40min. Then, 6.5g of silane coupling agent KH550 and 3g of functionalized silane monomer were added, stirred for 20min, heated to 80℃, and then 2g of triethylamine was added dropwise and stirred for 6h. After cooling to room temperature, the mixture was filtered and the precipitate was washed 5 times with anhydrous toluene (50g of toluene each time). Finally, it was vacuum dried at 60℃ and -0.09MPa for 8h to obtain the core-shell structure intermediate. S7: Under a nitrogen atmosphere and slightly positive pressure, 30g of a core-shell structure intermediate was added to 300g of anhydrous methanol and ultrasonically dispersed for 30min. Then, 22g of terminal amino hyperbranched polyamide was added and stirred for 30min, followed by stirring at 55℃ for 10h. After cooling to room temperature, the mixture was filtered and the precipitate was washed four times with anhydrous methanol (50g methanol each time). Then, it was dried at 80℃ and -0.09MPa vacuum for 12h. Subsequently, it was milled for 2h in a milling disc solid-phase mechanochemical reactor at 20MPa pressure and 200r / min speed (the temperature of the circulating cooling water in the milling disc was 20℃ during the milling process). Finally, it was pulverized and passed through a 300-mesh sieve to obtain a double-shell modifier. S8: Dry 800g of chlorinated polyvinyl chloride at 80℃ for 6h, then mix at 55℃ for 3min at 500r / min. Then add 31g of methyl tin mercaptan, 3.5g of calcium stearate, 2.5g of stearic acid, 1.5g of antioxidant 1010, and 1.5g of antioxidant 168 and stir at 1200r / min for 3min. After raising the temperature to 75℃, add 42g of functionalized cage-type silsesquioxane and 16g of rutile titanium dioxide and stir at 1200r / min for 4min. Then raise the temperature to 88℃ and add 85g of composite modified magnesium hydroxide, 30g of double-shell modifier, and 60g of chlorinated polyethylene. After stirring for 5min, raise the temperature to 115℃ and add 5g of polyethylene wax and 1.5g of ultraviolet absorber UV-531 and stir for 3min (at this time, the material temperature does not exceed 120℃). Finally, while stirring at 300r / min, water cool to 45℃ and discharge to obtain the mixture. S9: A co-rotating twin-screw extruder is used for melt blending treatment with a screw length-to-diameter ratio of 50:1, a feeding and conveying section at 145°C, a compression section at 155°C, a plasticizing section at 165°C, a homogenizing section at 175°C, a venting section at 170°C, a die head connection section at 180°C, a die head orifice at 175°C, a screw speed of 180 r / min, and a vacuum degree of -0.08 MPa or higher in the vacuum venting section. The extruded strips are immediately cooled and shaped in a constant temperature water bath at 40°C, then the surface moisture is dried by an air dryer, and after pelleting, they are dried at 85°C for 3 hours to obtain composite masterbatch. S10: The pipe is extruded and shaped using a single screw extruder with a screw length-to-diameter ratio of 30:1, a screw compression ratio of 3.5:1, a feeding section temperature of 155℃, a compression section temperature of 165℃, a metering section temperature of 175℃, a die head connection section temperature of 180℃, a die temperature of 182℃, a screw speed of 30r / min, a traction speed and an extrusion speed of 1.5m / min, and a vacuum degree of -0.08MPa in the vacuum sizing sleeve. After that, it is slowly cooled in a three-stage cooling water bath at 45℃, 35℃, and 25℃. The cooled pipe is then cut to a fixed length to obtain a toughened CPVC power cable protection pipe.

[0026] Comparative Example 1: Compared with Example 1, this comparative example only did not add "9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide" during the preparation of S1. All other steps and parameters were the same, and will not be repeated here. The toughened CPVC power cable protection pipe was finally obtained.

[0027] Comparative Example 2: Compared with Example 1, this comparative example only replaces the "functionalized cage-type silsesquioxane" added in the S8 preparation process with the "functionalized silane monomer" prepared in S1. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, toughened CPVC power cable protection pipe is obtained.

[0028] Comparative Example 3: Compared with Example 1, this comparative example only replaces the "composite coated magnesium hydroxide intermediate" added in the S4 preparation process with "nano magnesium hydroxide". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, toughened CPVC power cable protection pipe is obtained.

[0029] Comparative Example 4: Compared with Example 1, this comparative example only omits the addition of "silane coupling agent KH550 and functionalized silane monomer" in the preparation process of S6. All other steps and parameters are the same, and will not be repeated here. The toughened CPVC power cable protection pipe is finally obtained.

[0030] Comparative Example 5: Compared with Example 1, this comparative example only replaces the "double-shell modifier" added during the preparation process of S8 with the "core-shell structure intermediate" prepared in S6. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, toughened CPVC power cable protection pipe is obtained.

[0031] Comparative Example 6: Compared with Example 1, this comparative example only omits the addition of a "double-shell modifier" during the preparation of S8. All other steps and parameters are the same, and will not be repeated here. The toughened CPVC power cable protection pipe is finally obtained.

[0032] Performance testing: Flame retardancy testing: Referring to GB / T 2408-2021 standard, the vertical flame retardancy rating of 125mm×13mm×3mm samples of toughened CPVC power cable protective pipes prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was determined, and the test results are shown in Table 1.

[0033] Determination of smoke suppression properties: Referring to GB / T 8627-2007 standard, the smoke density rating of 25.4mm×25.4mm×3mm samples of toughened CPVC power cable protective pipes prepared in Examples 1-3 and Comparative Examples 1-6 of this invention was determined, and the results are shown in Table 1.

[0034] Impact resistance testing: Referring to GB / T 1043.1-2008 standard, the toughened CPVC power cable protective pipes prepared in Examples 1-3 and Comparative Examples 1-6 of this invention were made into Type A notched specimens with dimensions of 80mm×10mm×4mm (notch bottom radius of 0.25mm, notch depth of 2mm). The impact strength (kJ / m²) was measured after conditioning in a standard environment of 23℃ and 50% relative humidity for 24 hours, followed by constant temperature conditioning in a -20℃ low-temperature constant temperature chamber for 6 hours, and then under the conditions of -20℃, pendulum energy of 2.75J, and impact velocity of 2.9m / s. 2 The measurement results are shown in Table 1.

[0035] Determination of aging resistance: Referring to GB / T 16422.3-2014 and GB / T 1040.2-2022 standards, the cable protection tubing materials prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were made into type 1A dumbbell specimens (total length 150mm, parallel section width 10mm, thickness 3mm), and measured under a UVB-313 fluorescent ultraviolet lamp at 0.71W / (m²). 2The tensile strength (MPa) at a tensile speed of 5 mm / min was measured before and after 168 h of exposure (4 h of UV irradiation at 60℃ and 4 h of condensation at 50℃ as one cycle, with alternating cycles) under conditions of ·nm)@310nm and a spacing of 150 mm. The results are shown in Table 1.

[0036] Determination of heat resistance: Referring to GB / T 1633-2025 standard, 10mm×10mm×4mm specimens made from the toughened CPVC power cable protective pipes prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were conditioned for 24 hours in a standard environment of 23℃ and 50% relative humidity. The Vicat softening temperature (℃) of the specimens was determined using the A50 method (load 10N, heating rate 50℃ / h). The results are shown in Table 1.

[0037] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-6

[0038] Data Analysis: As can be seen from Table 1, the toughened CPVC power cable protection pipe prepared in the embodiments of the present invention has excellent flame retardancy, smoke suppression, impact resistance, aging resistance and heat resistance.

[0039] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A toughened CPVC power cable protection pipe, characterized in that, The composition by weight includes: 40-42 parts of functionalized cage-like silsesquioxane obtained by triethylamine catalytic addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and vinyltriethoxysilane to obtain a functionalized silane monomer, followed by in-situ hydrolysis and condensation with silane coupling agent KH550; 80-85 parts of composite modified magnesium hydroxide obtained by stepwise in-situ coating modification of nano-magnesium hydroxide with tin tetrachloride pentahydrate, zinc sulfate heptahydrate and sodium borate decahydrate to obtain a composite coated magnesium hydroxide intermediate, followed by surface grafting modification with silane coupling agent KH550; and tin tetrachloride pentahydrate and zinc sulfate heptahydrate first undergoing... Hollow zinc hydroxystannate cores were obtained by hydrothermal crystallization at 160℃ and calcination at 600℃. Then, core-shell structure intermediates were obtained by in-situ grafting modification with silane coupling agent KH550 and functionalized silane monomers. Subsequently, the intermediates were modified by grafting with terminal amino hyperbranched polyamide and solid-state mechanical chemical milling to obtain a double-shell modifier of 28-30 parts; thiol methyltin 30-31 parts; calcium stearate 3-3.5 parts; stearic acid 2-2.5 parts; antioxidant 2-3 parts; rutile titanium dioxide 15-16 parts; chlorinated polyethylene 55-60 parts; polyethylene wax 4-5 parts; ultraviolet absorber 1-1.5 parts; and chlorinated polyvinyl chloride 780-800 parts.

2. The toughened CPVC power cable protection pipe according to claim 1, characterized in that, The mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, vinyltriethoxysilane, and triethylamine is 69.2:62-64:

6.

3. The toughened CPVC power cable protection pipe according to claim 1, characterized in that, The mass ratio of the functionalized silane monomer to the silane coupling agent KH550 is 100:73-75.

4. The toughened CPVC power cable protection pipe according to claim 1, characterized in that, The mass ratio of the nano-magnesium hydroxide, tin tetrachloride pentahydrate, zinc sulfate heptahydrate, and sodium borate decahydrate is 120-130:28:48.3:

25.

5. The toughened CPVC power cable protection pipe according to claim 4, characterized in that, The mass ratio of the composite-coated magnesium hydroxide intermediate to the silane coupling agent KH550 is 200:5-6.

6. The toughened CPVC power cable protection pipe according to claim 1, characterized in that, The mass ratio of tin tetrachloride pentahydrate to zinc sulfate heptahydrate is 42:34.5-35.

7. The toughened CPVC power cable protection pipe according to claim 6, characterized in that, The mass ratio of the hollow zinc hydroxystannate core, silane coupling agent KH550, and functionalized silane monomer is 30-32:6-6.5:

3.

8. The toughened CPVC power cable protection pipe according to claim 6, characterized in that, The mass ratio of the core-shell structure intermediate to the terminal amino hyperbranched polyamide is 25-30:18-22.

9. The toughened CPVC power cable protection pipe according to claim 6, characterized in that, The solid-phase mechanochemical milling modification treatment is as follows: milling is carried out for 2 hours at a pressure of 20 MPa and a rotation speed of 180-200 r / min using a milling disc-shaped solid-phase mechanochemical reactor.

10. A method for preparing a toughened CPVC power cable protection pipe according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Dry chlorinated polyvinyl chloride at 80℃ for 5-6 hours, then mix it with methyltin mercaptan, calcium stearate, stearic acid, antioxidant, functionalized cage-type silsesquioxane, rutile titanium dioxide, composite modified magnesium hydroxide, double-shell modifier, chlorinated polyethylene, polyethylene wax, and ultraviolet absorber to obtain a mixture. S2: The composite masterbatch is obtained by melt blending using a co-rotating twin-screw extruder, water cooling and shaping of the extruded strip, blowing and pelletizing, and drying at 85℃ for 2-3 hours. S3: The pipe is extruded and shaped using a single screw extruder, then water-cooled and cut to a fixed length to obtain a toughened CPVC power cable protection pipe.

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